2.7 μm emission of Er³⁺-doped LiNbO₃ crystals and its thermal effect

We have studied the 2.7 μm emission of singly Er³⁺-doped and Er³⁺/Dⁿ⁺-codoped (Dⁿ⁺ = Yb³⁺, Mg²⁺, Zn²⁺ and In³⁺) LiNbO₃ crystals, as well as its thermal effect. The emission and absorption cross section spectra were calculated from the measured emission spectra. The results show that the peaking emission and absorption cross section values vary around 1 × 10^-20 cm² and increase slightly with the increased rare-earth ion concentration. The codoping of optical-damage-resistant ions Mg²⁺, Zn²⁺ and In³⁺ tends to reduce the cross section value. The different effects are related to the fact that the rare-earth/optical-damage-resistant ion doping induces successive increase/decrease of intrinsic defects, slight spectral broadening/narrowing of Er³⁺ absorption (emission) band, and hence slight increase/decrease of Er³⁺ absorption (emission). The thermal effect study shows that the peaking emission intensity decreases by ∼78% with the temperature rise of only 54 ^°C from 24 ^°C.